Answer:

Step-by-step explanation:

1. since the equations equal each other
2x+19=x+7
-x -x
x+19=7
-19 -19
x= -12
sub into y= x+7
y= -12+7
y= -5
2. x+2y=-7
<span>x+y+23=0
i don't know what the second equation is equal to, i'll assume 0
2y=x-7
y=1/2x-7/2
sub this into x+y+23=0
x+1/2x-7/2+23=0
3/2x+39/2=0
-39/2 -39/2
3/2x= -39/2
x=-39/2 / 3/2
x= -13
sub into y=1/2x-7/2
y=1/2(-13)-7/2
y= -10
3. </span>x+5y=2
<span>x=-4y+5
</span>sub x=-4y+5 into x+5y=2
-4y+5+5y=2
y+5=2
-5 -5
y= -3
sub y =-3 into x =-4y+5
x=-4(-3)+5
x= 17
4. 3x+y=9
<span>y=-5x+9
</span>sub -5x+9 into 3x+y=9
3x+(-5x+9)=9
3x-5x+9=9
-2x+9=9
-9 -9
-2x=0
x=0
sub into y=-5x+9
y=-5(0)+9
y=9
I find it best to switch everything exponents when taking derivatives.
F(x) = 7/x
Same as..
F(x) = 7x^-1
Take derivative..
F'(x) = -7x^-2
Plug in x = 1
F'(1) = -7(1)^-2
F'(1) = -7
Answer:
2 for each ride
Step-by-step explanation:
50-26=24 she used 24 so far
24/12=2 each ride was 2
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